Tfi 467 
.G22 
Copy 1 



THE PROTECTION 



OF 



STRUCTURAL STEEL 



COPYRIGHTED 1904, 

By George N. Gardiner & Son 
15 William Street, New York. 



TA--H7 

Gc-2."Z_ 



Two Oocits Received j 

SEP 20 1904 
^J5o»yrfeht Envy 

CLASS C& XXo. No. I 

COPY B 






£/?<K3too 



THE PROTECTION OF STRUCTURAL STEEL. 

The present method of constructing buildings, 
calling, as it does, for a framework of steel, has set 
many minds working, and has developed a number 
of serious problems for solution. 

All know that the modern skyscraper is a network 
or cage of steel girders and beams, and that the en- 
tire weight of the floors and enclosing walls must 
be borne by this metal structure. Steel cage con- 
struction has been in vogue for about fifteen to 
twenty years, and up to the present time it might 
truthfully be said that it is in an experimental 
stage. 

One of the most serious of all the problems con- 
fronting engineers and architects to-day is how to 
preserve this steel and protect it from the rust or 
corrosion that so quickly attacks it. 

In the case of the Hotel Savoy, which was re- 
cently torn down in Boston, it was found that the 
steel supports had badly rusted. Its steel frame 
had been coated with a supposedly rust-preventing 
linseed oil paint, which its builders thought would 
prove sufficient protection for many years. A 
number of the beams were found to be corroded, 
and rust scales covered much of the surface. Rivets 
were also rusted, and experts were satisfied that 
the effect of the oxidation would have been serious 
in time if the conditions had been allowed to con- 
tinue. And how many huge buildings are in the 
same condition to-day? 

As modern skyscrapers are business investments, 
the same as bonds or stocks, and must yield an ade- 



quate return for their initial outlay and mainte- 
nance expenses, it is vital to all concerned primar- 
ily that the steel should be so protected from rust 
that the structure should last for a great number 
of years. 

This framework cannot be painted regularly, 
like bridge and other work, and, being sealed up 
in masonry, where it cannot even be inspected once 
the building is completed, the only preservation 
must be applied at the first. The dangerous effect 
of oxidation can readily be appreciated. 

There is hardly another metal that is liable to 
such rapid deterioration as steel, and it is abso- 
lutely necessary to protect it with a coating that 
will hermetically seal it from oxygen, moisture or 
C0 2 . Some absolutely impervious coating that 
shall be neutral, thus containing no element that 
will harm the steel itself or combine with gaseous 
or other matter, to form destructive chemical com- 
pounds. 

This matter of protecting steel has now become 
an important and serious one, and it is only a ques- 
tion of a short time when architects and engineers 
will pay as much attention to protecting steel struc- 
tures with rustless coatings as they do now to the 
caisson work of the foundations and the general 
structural strength of the building, because the 
structural strength of the building is weakened by 
the amount of corrosion that takes place. And, 
furthermore, they will have the painting inspected, 
for the painting will not be done, as it is done now, 
in a shiftless and careless way — the majority of 
cases not under the supervision of any one con- 
nected with the job. 

What means are employed to prevent the oxida- 
tion of steel ? Very likely a coat of red lead, or some 
oil paint. Red lead is a carrier of oxygen, as is 



linseed oil. Either will convey moisture or C0 2 
to the metal underneath them, and oxidation con- 
tinues under an apparently good coat of paint. 

A well-known expert has stated that more than 
half of the tall buildings in New York and other 
cities will have to be pulled down in a few years, 
because their supporting steel structures will have 
rusted out until they become unsafe. 

We have given this subject of protecting iron 
and steel our careful attention, and have had the 
experience and assistance of some of the best chem- 
ists to aid us.. We know that if a clean steel sur- 
face is painted, and after a short time the metal is 
found to be corroded, or rust has commenced under- 
neath the surface of the paint, either the paint con- 
tains moisture itself, is a carrier of oxygen, or dries 
with a porous surface, thus absorbing moisture 
and communicating it to the metal underneath; in 
either case, it is no real protection, and it is prob- 
ably actually dangerous in that it hides the oxidiz- 
ing process from observation, if it does not really 
aid it. 

Former devotees of red lead are beginning to 
admit its failure as a non-oxidizing agent. Oil 
paints containing pure linseed oil also fail to pro- 
tect, as both of these products absorb moisture and 
conduct it to the metal, and linseed oil dries, not 
by evaporation but by oxidation. 

None of the so-called "rust-proof" paints afford 
real protection, as they all depend for their vehicle 
on linseed oil, and therefore the best constructed 
pigments are rendered porous through their 
vehicles. 

Asphalt is out of the question, as its porosity is 
very great, and its durability, after having its 
molecular condition destroyed for the purpose of 
compounding, is not to be depended upon. 



Graphite has been very largely used, but graphite, 
although it has uiauy good qualities, will not do 
as a paint. The greasy nature of this product 
which does not change no matter how finely it is 
ground (being different from leads and other 
colors) will never permit it to really combine with 
the oil. The two are not homogeneous, and their 
specific gravities are so different, that, after the 
graphite paint is dry, the carbon particles separate 
from the rest of the surface and allow C0 2 to attack 
the metal. 

Graphite has been used successfully as a lubri- 
cant, but it has never been possible to have it really 
combine in a paint with the oils and other matter, 
and nothing suitable for a paint has ever been 
found that will hold it in solution and with which 
it will really combine. It is merely held in sus- 
pension. Take some substance, say isinglass, soak 
it in oil, and vou can readilv see that it will not 
combine to make a mixture. Oil has no affinity 
for it. Grind this substance as fine as you please, 
each particle is still as insoluble in oil as it was 
as a whole. The form is changed but not the sub- 
stance. Such particles may be held In suspension 
in a paint, but do not combine with it. There is 
no homogenity, consequently, a's far as permanent 
results are concerned — no paint. 

A number of coatings have also been made of 
the residuum from the oil refineries. Thev all 
deteriorate rapidly when exposed to the atmosphere 
or moisture, entirelv losing their efficiency. 

The oxidation of steel has been proved to go on 
under any of these paints, even when applied in 
successive layers. There are many coatings used 
which contain some ingredient more or less harm- 
ful to steel. It is therefore evident that a protecting 
coating to be really efficient must have these quali- 



ties. It must dry free from porosity and contain no 
moisture itself. It must have no affinity for oxygen, 
and contain no element injurious to the metal. It 
must be neutral, and should dry with very little 
sioss, so as to effect a better hold for cement or 
mortar. 

"Gardiner's Anti-Rust Paint" is a neutral product, 
which hermetically seals the surface of the metal 
to which it is applied, thus preventing any action 
taking place whatsoever. This coating is brown 
in color, easy of application, dries in an hour, and 
after the steel has received this protecting coat, any 
form of paint or color decoration can be applied 
over it. It is very durable, and where the coated 
surface is sealed up, as in a subway tunnel, or 
building construction where it is hprd to get at 
the parts to repaint, is invaluable, affording an 
absolute protection against corrosion, Being 
neutral, non-porous and protected from wear and 
tear, theoretically, it should last forever. It is 
well known that the latent heat of steel produces 
a condensation of hydrometric moisture (or sweat- 
ing) and this composition remedies this great evil. 

This coating has been used in various ways, es- 
pecially on metal where exposed to moisture, and 
its value as a protection against corrosion, even 
at sea, has been fully demonstrated. 

A very simple test which shows the superiority 
of this composition over red lead can be made by 
painting a small circular surface on a piece of 
glass, with red lead and oil, and a similar surface 
on the same or another piece of .^lass with this 
composition. After the two paints have dried, a 
few drops of water should be placed in the centre 
of each painted section, and this should be covered 
with a tumbler to prevent evaporation. In a short 
time the surface of the red lead will be found to 



be puckered, showing that the water has passed 
underneath and through it, while this coating will 
still adhere firmly to the glass. 

The makers of this coating have given their entire 
time and attention to the protection of steel and 
iron surfaces from corrosion for the past thirty-five 
years. They are not paint manufacturers in the 
general acceptation of the term, confining them- 
selves entirely to making coatings for the protec- 
tion of iron and steel, and are regarded as experts 
in this special field. Their several coatings will 
meet every requirement for protection in steel con- 
struction. 

This paint has received the careful scientific ex- 
amination of chemists and others and has been 
proved to their satisfaction to be compounded on 
scientifically correct principles, and will absolutely 
exclude carbon dioxide, without which there can be 
no rusting of steel.. Sulphurous acid will not 
affect it and it will withstand sulphuretted hydro- 
gen and carbonic acid gas. 

A very conclusive test was made some time ago 
.showing the waterproof qualities of "Gardiner's 
Anti-Rust Paint." An ordinary hard red brick 
was baked in an oven so as to exclude all the mois 
ture it contained. It was then coated with two 
coats of this paint and carefully weighed ; this was 
then submerged in water for 48 hours and weighed 
again, and the weight had not increased a particle, 
showing that the brick had not absorbed any of 
the water. It was immersed again in water and 
left several months, and at the end of even that 
longer period showed conclusively that it had been 
impossible for the water to pass through the film 
of paint, although the brick on the other side was 
ready to absorb it like a sponge. This same test 
was made with many linseed oil paints, red leads, 



and other coatings, and none of them could with- 
stand the action of the water longer than 12 hours. 
The brick covered with the best quality of red lead 
and linseed oil paint was found at the end of 24 
hours to be saturated. 

For use in building construction this coating 
has no equal, as it is easily applied to steel, and 
dries almost immediately. It is brown in color, 
and is packed in 5-gallon iron drums. It is the 
most durable paint now on the market, and a well- 
known chemist has declared will add 20 years to 
the life of the steel it covers. For subways and 
tunnels, where humidity abounds and moisture is 
apt to collect and rapidly corrode the metal, it will 
be found especially valuable, and, as it is capable 
of withstanding sulphuretted hydrogen, it will be 
found the only paint suitable for railroad bridges 
and similar work. Another very valuable feature 
of this coating is that it can be applied in cold or 
damp weather. 

We believe that as soon as this matter is better 
understood architects and engineers will come to 
regularly specify that steel for the construction of 
their buildings shall be coated with this paint, and 
that they will insist upon its use. 

There is nothing else to-day known to science 
that will absolutely protect steel from corrosion 
permanently. As to the truth of the statements 
we have made, we beg to refer to the quotations 
following, which are made from standard authori- 
ties. We should be glad to give you any further 
information on this subject, or will have a repre- 
sentative call at your convenience. 

George N. Gardiner & Son, 
15 William Street, New York. 



FROM 

INSURANCE ENGINEERING EXPERIMENT 
STATION. 

EDWARD ATKINSON, Director, 
No. 31 Milk Street, Boston, Mass. 



Extract from Report No. IX. 
THE PROTECTION OF STEEL FROM CORROSION. 



PAINTS. 



The subject of paints will now be taken up for thorough 
investigation, apparatus having been invented and methods 
of testing devised, which are submitted in this report. From 
the best information that I have been able to gather, it would 
appear that any paint on which reliance can be placed for 
the protection of steel or other metal from corrosion must 
be one which dries by evaporation or sets like hydraulic 
lime: it must not be one ivhich hardens by the oxidation of 
the oil or any other ingredient of the compound in which lead 
or other pigments are mixed. Steel, having great affinity for 
oxygen, is corroded by the oxidation of the oil itself, while 
the outer surface of the paint, exposed to the air, may stop 
moisture from penetrating for & very considerable period 
of time, or until the oxidation of the body of the oil has re- 
leased the lead or other pigments, thus exposing the steel 
surface to a humid atmosphere by the complete destruction 
of the paint. 

Steel may be protected by paints, cements or coverings 
that have more affinity for oxygen than steel itself. Such 
coverings will absorb from the atmosphere, even when humid 
or loaded with particles of oxidizable matter, all that would 
tend to corrode before it reaches the steel. 

It is in that direction that efforts have been made, and 
are now being made, for making paints or thin veneers for 
the covering of steel that will neither corrode it by their own 
contact nor permit corrosive elements to reach the steel. 
Such paints or veneers must not be brittle. They must be 

8 



sufficiently elastic to yield to the contraction and expansion 
of the steel without cracking or chipping. We have informa- 
tion of one such paint, made for many years in England by 
a secret process, which has been used upon the British ships 
for a long period and now being made in this country. Under 
these conditions the investigations which we now propose to 
undertake seem to the undersigned to be of the gravest 
importance. 

Respectfully submitted, 

Edward Atkinson,, 

Director. 



Charles J. Eames, 

APPLIED 

CHEMISTRY AND METALLURGY, 

99 Water Street, 

New York. 

February 4, 1904. 
Messrs, George N. Gardiner & Son, 

Gentlemen : 

Referring to your inquiry regarding tests made by me 
of your 

"ANTI-RUST PAINT." 

The subject of protecting iron and steel surfaces by paint, 
has long been a study by me. I fully determined, by experi- 
ments, that all paints composed of lead in any form, and lin- 
seed oil, did not protect the surface from oxidation, evapora- 
tion of turpentine, leaving the surface porous. 

It is now more than two years since I commenced experi- 
menting with your "Anti-Rust Paint." An ordinary hard 
red brick coated with your paint resisted the action of moist- 
ure. Iron and steel plates (polished) coated with your paint 
showed no oxidation after several months' exposure. The 
surface of cast-iron coated with your paint, after an expos- 
ure to all weathers, was protected entirely from oxidation. 

I have no hesitation in stating that your "Anti-Rust 
Paint" is waterproof, and resists the action of deleterious 
gases. 

Respectfully yours, 
(Signed) Charles J. Eames- 



Extracts from 

METALLIC STRUCTURES. 

CORROSION AND FOULING. AND THEIR PREVEN- 
TION. 

By JOHN NEWMAN. 

Published by Spon, London. 1896. 



The maintenance and present : ndition of iron and steel 
used in various forms in engineering and building construc- 
tion are likely to demand increasing attention, as, either from 
fatigue,, vibration, corrosion, decomposition or general deteri- 
oration, the metal may have become either changed in its 
characteristics or be so impaired as to be no longer the same 
metal as when erected, or of sufficient dimensions to sustain 
the load it originally was well able to support. 

The number of metallic structures requiring either 
strengthening or renewing must increase, and,, in thoroughly 
opened-up countri--. it is probable their restoration will soon 
be an important branch of engineering science. It is one in 
which special skill is necessary, not only to ascertain the real 
condition of a structure,, but also to arrest any elements of 
decay, and to restore it to its original strength. Metallic rail- 
way and road bridges, and public buildings of importance, 
have more or less continued attention bestowed upon them, 
but the care is usually, and not unnaturally, commensurate 
with the size of the bridge or building, and its public position 
and importance, notwithstanding that in the smaller struc- 
tures the surfaces may be more ex ae :"_. an ] : rrosion greater 
in comparison with the sectional area of the metal. Private 
warehouses and buildings are usually left either to a tenant 
to keep in repair, which generally means a coat or two of 
cheap oil paint every few years, or are under the supervision 
of some local builder whose knowledge of the circumstances 
which caused corrosion or depreciation is not, to say the least, 
too profound. 

Structures and buildings supported by iron or steel col- 
umns and pillars should be occasionally examined by an 

10 



expert engineer, for, in many cases, although the iron work 
may be well designed, so far as regards strength, to carry 
any load, and with the view to easy erection, the instances 
are comparatively few in which their preservation from 
corrosion has been specially considered. (Page 2.) 

Metals, unlike Portland cement, which, to a certain limit- 
ing period, increases, or should increase, in strength with 
age, suffer a diminution of strength, however slow it may be, 
almost from the time they are used. To attempt to prevent 
corrosion without knowing the cause of such action can only 
by chance be successful, for the rapidity, and therefore the 
power of corrosive influences, depends upon the conditions 
and circumstances in which the metal is placed. Sir B. 
Baker has concisely declared that "it is the deviation from 
the average which really is so important in the design of 
engineering works." In a few instances it has happened that 
the reports of the most eminent professors of chemistry and 
the results obtained in engineering practice have not agreed, 
and yet undoubtedly both have been correct. The conditions 
under which the substances or liquids have been used has 
been the cause of the dissimilarity. In the laboratory, the 
examination is conducted with the greatest minuteness, and 
time is allowed for important action, and attention is spe- 
cially directed to discover everything that can be detected 
regarding the information desired. If all the conditions are 
not clearly stated under which a substance or liquid is to 
be used, a report will most probably be either too favorable 
or unfavorable, although perfectly correct so far as probable 
results under laboratorial circumstances are concerned. It 
is necessary for an engineer to fully explain to an analytical 
chemist the corrosive influences to which any substance will 
be exposed, and the circumstances in which it will be used. 
(Pages 3-4.) 

Although mechanical tests are usually of more value to 
the engineer than chemical analyses, still the latter are always 
valuable, and, so far as corrosion is concerned, its probable 
progress cannot be determined except from the probable 
chemical action. (Page 5.) 

The number of old bridges, which is generally being less- 
ened, receiving the necessary attention, subject to increased 

11 



loads, additional traffic, and at an accelerated speed, is not 
inconsiderable, and it is the smaller bridges rather than those 
of considerable span that perhaps more especially require 
inspection periodically, as they can hardly receive the same 
amount of care as any important structures, and yet the 
consequences of failure may be very serious indeed. The 
examination should be made by experts in metallic construc- 
tion and repairs, or those trained to make such reports, and 
the time may come when there will be specially appointed 
engineers to make such examinations and reports, suggest 
precautionary and remedial measures, and carry them into 
execution. (Pages 7-8.) 

Mr. Ewing Matheson, in his paper, "Steel for Structures" 
(Minutes of Proceedings, Institute C. E., Yol. LXIX), wrote: 

"The preservation of iron from rust is not in this country 
sufficiently considered." Steel being now so much used, and 
the sectional area reduced in many instances as compared 
with iron, the preservation of the metal in its original section 
is of even more importance than formerly. (Page 3.) 

Corrosion and general deterioration, if allowed to pro- 
ceed unchecked, must culminate in failure. (Page 5.) 

In considering the various causes and influences that, in 
some way or other, produce corrosion, it is well to remember 
that probably in the whole range of the science and the art 
of construction there is nothing more difficult to contend 
against than the decay of materials, or anything requiring so 
much constant care and diversified 'treatment, consequent 
upon the different nature of the materials, the Vcvrious objects 
to which they are applied, and the changeableness of the 
influences that cause deterioration and decomposition. 
Almost from the moment of their manufacture, the metallic 
portions of a structure may be said to be subject to the com- 
bustion of decay, which, it is decreed, must sooner or later 
overtake them; the aim of the engineer is to reduce to a 
minimum every deteriorating influence. (Page 11.) 

Experiments have shown that corrosion, not exteriorly 
aided by galvanic action, on steel plates increases progress- 
ively. Those of Mr. Andrews, E. P. S., show it to be 50 per 
cent, more the second year, compared with the first. 
(Page 12.) 

12 



"Neither bright iron nor steel will rust in pure water or 
in pure air. The presence of carbonic acid, or some similar 
agent, seems necessary, although the final product may be 
destitute of carbon." (Page 13.) 

Oxygen alone does not cause corrosion, as will be gathered 
from the experiments of Dr. Grace Calvert, F. R. S., who, in 
describing some he made with perfectly clean blades of steel 
and iron, exposed for four months to the action of different 
gases, in order to determine whether the oxidation of iron 
is due to the direct action of the oxygen of the atmosphere 
or to the decomposition of its aqueous vapor, or whether the 
very small quantity of carbonic acid which it contains deter- 
mines or intensifies the oxidation of metallic iron, found 
that the blades showed the following results : 

Dry oxygen : No oxidation. 

Damp oxygen : In three experiments, one blade only was 
slightly oxidized. 

Dry carbonic acid: Slight appearance of a white precipi- 
tate upon the iron, found to be carbonate of iron. 

Dry carbonic acid and oxygen: No oxidation. 

Damp carbonic acid and oxygen : Oxidation very rapid. 

Dry and damp oxygen and ammonia: No oxidation. 

These experiments tend to show that carbonic acid, and 
not oxygen or aqueous vapor, is the agent which determines 
the magnitude of the oxidation of iron in the atmosphere. 
Therefore, carbonic acid in a damp atmosphere is a powerful 
and active agent in causing corrosion, and it was further 
shown by experiments that when iron was immersed in water 
containing carbonic acid it rapidly oxidized. (Page 16.) 

In fact, so long as man exists on this earth in its present 
state it is decreed that oxygen and carbonic acid shall 
be present. As carbonic acid (CO„), which is always in the 
atmosphere in varying quantity, in presence of moisture, is 
so active a corrosive agent, what are the chief causes of it? 
The breath of animals, the decomposition of vegetable 
and animal matter (hence the importance of no vegetable 
substance resting upon a painted surface), limestone, chalk 
and all calcareous stones in which it exists in a solid form, 
the presence of an acid setting it free. (Pages 17 and 18.) 



13 



The experiment of the combustion of iron and steel wire 
in oxygen gas is well known, and is an example of this. 
Iron, by some authorities, is not considered to decompose water 
in the absence of air at ordinary temperatures without con- 
tact with some substance electro -negative to it. Prof. Tyn- 
dall's experiments and labors show that air is laden with 
myriads of germs and agents of decomposition ready to settle 
down and develop upon matter suitable to their growth. 
Fermentation has been described as a change in the elements 
of a body composed of oxygen, carbon and hydrogen without 
nitrogen, but putrefaction as a change effected in the ele- 
ments of a body composed of carbon, oxygen, hydrogen and 
nitrogen. Dr. Brewer has briefly and well explained that 
"the carbon, oxygen, hydrogen and nitrogen of the original 
substance, being separated by decomposition, reunite in the 
following manner: (1) carbon and oxygen unite to form 
carbonic acid; (2) oxygen and hydrogen unite to form water; 
(3) hydrogen and nitrogen unite to form ammonia." 

Dr. Grace Calvert's experiments show that carbonic acid 
and moisture produce rapid corrosion, and in the case of the 
structures mentioned must be added sulphuric acid and 
chlorine, two very energetic corrosive agents. (Page 24.) 

If bridges, roofs, promenade and landing piers, and simi- 
lar structures, had the care bestowed upon them that iron 
and steel ships receive, their serviceable life would be much 
prolonged. (Page 133.) 

In bridges, roofs and unsubmerged structures the extent 
of appreciable corrosion chiefly depends upon the attention 
given to them, the removal of the oxide scale before painting, 
the complete covering of the metal with an anti-corrosive and 
insulating coating, preferably possessing the power of hard- 
ening under water, the quality of the material, its freedom 
from galvanic action, and the nature of the atmosphere and 
climate in which the structures are erected. In fact, their 
serviceable life is governed by the care bestowed upon them 
in keeping them clean, and entirely equally coated, which 
necessitates frequent examination, and renewal of the pro- 
tection of the surfaces. Then, and' then only, may their 
serviceable life, so far as regards corrosion, be considered as 
long-continued. In the case of submerged structures, the 
circumstances are different, for, except by divers, or by the 



14 



use of compressed-air apparatus in some form or other, they 
cannot be inspected, nor can they be repainted in water, and 
the subterranean portion cannot be examined. The dura- 
tion of the parts of a structure which are either constantly 
submerged or buried in the earth, as in the case of piles or 
columns, can only be deductively estimated from the behavior 
of similar works subject to like conditions and circumstances. 
(Page 134.) 

Not many lines of a specification are generally reserved 
for protection against corrosion, and some elaborate specifica- 
tions in all other respects may refer to painting in something 
like the following few words, "all iron surfaces to be painted 
with two coats of metallic paint and oil, and with an addi- 
tional coat of lead and oil when the structure has been 
erected, the time of painting the last coat to be determined 
by the engineer." Thus the preservation of the metal from 
corrosion is only indirectly referred to, the covering of the 
metal with some substance being alone mentioned. Such 
a specification may be regarded as one which simply cares 
little for the maintenance of the original strength of a 
structure so long as it is erected. 

In the case of any metallic structure which can only be 
occasionally inspected by an expert engineer, or when it has 
to be erected abroad, special provision should be made against 
corrosive influences (Page 8). 

Obviously, there is more carbonic acid present in crowded 
cities and manufacturing towns than in the open country. 
The quantity in the atmosphere is, however, very small, it 
being approximately, according to Dr. Angus Smith, in 
the open parts of London, 3 parts by volume in 10,000 parts 
of air. In the hills of Scotland 3.3 per 10,000, and in London 
streets 3.8 per 10,000. In the streets of Manchester during 
fog 6.8 per 10,000. In close buildings, it averages 16 per 
10,000, and usually from 7 to 10 parts in houses (Page 18). 

There are other agents, whether caused by smoke, the 
steam of locomotives, or heat, that accelerate corrosion, and 
among them sulphuric and sulphurous acid (Pages 18-19). 

Corrosive action increases with the temperature, and at 
freezing point Fahrenheit it is very little. The effects of tem- 

15 



perature are very considerable in chemical action, and a 
certain degree of heat or cold is necessary to produce the 
greatest activity. Experience in Sweden indicates that it. is 
the constant changes of temperature from heat to cold, or 
cold to heat, that weakens the iron in rails. Mr. Sand- 
berg states that this explains why the breakage of rails 
generally take place in the autumn or spring and not when 
the metal is for some days at a constant temperature 
(Page 22). 

Experience has proved that very small quantities of car- 
bonic, sulphuric and sulphurous acids will cause rapid cor- 
rosion of iron or steel. Where the better qualities of coal 
are consumed, as in non-manufacturing districts, there is 
not so much sulphur in the air, and consequently the amount 
of sulphurous or sulphuric acid to be brought down by rain, 
and so deposited upon any metallic surface, is reduced ; how- 
ever, sulphur set free from any substance in the presence of 
moisture will act corrosively and deleteriously on iron or 
steel (Pages 23-24). 

Oils in general are known to absorb oxygen when in con- 
tact with the atmosphere. Some oils become thereby solidi- 
fied and hardened, while others retain their liquid condition; 
the first mentioned being usd for varnishes, the latter for 
lubricants (Page 272). 

A peculiar property of oil is that it will permeate what 
may be otherwise regarded as a sealed and water-tight sub- 
stance (Page 276). 

All paint used in bridges or structures subject to vibra- 
tion should be of such consistency as to be elastic, or it 
will crack or become detached. It should always be remem- 
bered, in choosing a paint, that a metal surface is unlike a 
wooden one. The former is not absorbent, and the paint has 
to be so made that it will adhere to it. Timber, however, to a 
certain extent, absorbs or attracts the paint, therefore, a 
paint that may be excellent for wood may be of little or no 
use for metals (Page 179). 

Carbonic and. nitric acids are most injurious to lead. 
Carbonic acid generally exists in the atmosphere, and it 
readily attacks lead in the presence of moisture ( Page 203). 

16 



In Iron, of the 31st of March, 1893, is an article by the 

author of this book, which the following 1 paragraph occurs : 

"Although oil paints are well adapted for coating wood, 
for metallic surfaces they are not so suitable. 

Raw linseed oil impregnates wood more than boiled oil 
and forms a kind of resinous adjunct which is to be desired, 
but it does not do so in the case of metals; therefore, its 
chief object is to prevent moisture reaching the surface of 
the metal, for while moisture, i. e., a moderate degree of 
wetness, does not affect the oil, both light and air have a 
deteriorating effect upon it, and damp or moist air especially 
so, inasmuch as it becomes partly dissolved by it and as- 
sumes a liquid form, particularly when the air is charged 
with moisture and no evaporation takes place. The oil has 
another special purpose, viz. : that of causing the pigments 
or other ingredients of the paint to adhere to the surface 
and to become a united mass or thick liquor. Hence the oil 
may be said to be by far the most important constituent of 
what are called oil-paints, and the importance of its purity 
is great; and, as it is liable to deterioration from such 
causes as those referred to, it can hardly be said that it is 
suitable for exposed work; and when applied to engineering 
metallic structures in the open air, its anti-corrosive and 
protective life is short, for, the damp air having dissolved 
it sufficiently, this action only being a question of time, how- 
ever slow its progress may appear to be, moisture will per- 
meate the coat of paint, or rain be forced in by wind, the 
consequence being that the metallic surface becomes cor- 
roded, and as rust forms the paint either blisters or more 
frequently becomes detached. One reason why ordinary oil- 
paints are not well adapted for out-door ironwork is that the 
turpentine usually employed in making them is distilled 
from impure turpentine by the medium of water, the volatile 
oil being so collected and the resin remaining; it is, there- 
fore, a volatile oil useful in the case of painting wood, but 
not so with comparatively non-absorbant substances, such 
as iron or steel. As a rule, the greater the quantity of tur- 
pentine in oil-paint, the more likely it is to have a dry scale 
on its outer surface" (Pages 270-271). 

Oils are sometimes agitated with a small quantity of sul- 
phuric acid in order to get rid of impurities. If this acid 
is not subsequently removed it has a corrosive effect on iron 
or steel, and also acts prejudically on the oils (Page 274). 



17 



It should he ascertained that the oil used to make any 
paint for metal work does not contain any acids, for many 
oils do, and, therefore, instead of being a n //-corrosive, may 
be actively corrosive (Page 274). 

Chemical action is not desirable in a paint for metals, 
unless it can be proved that it does not in any way affect 
their strength and durability. A physical, physiological and 
toxical action is to be desired in order to prevent corrosion 
and fouling by vegetable or animal life or micro-organisms, 
but the antiseptic power should be as permanent as possi- 
ble, and therefore its volatilisation and solubility in water 
should be prevented as much as practicable, or the utility 
of the antiseptic and anti-corrosive agents is destroyed; in 
fact, durability and insolubility are of the greatest impor- 
tance. The chemical action of drying, hardening and ad- 
hesion to the metal, yet not to such a degree as to cause 
cracking, or to destroy the required elasticity of the paint, 
but yet sufficient to make a moisture and air-tight covering. 
The mechanical action of penetration to and filling the pores 
of a metal, and the all-important one of sealing the surfaces 
so that no air and moisture can reach them. The mechanical 
action of an anti-corrosive paint in closing the pores of the 
metal is most valuable, as it prevents any subsequent ab- 
sorption of moisture. If the surface be sealed from air, 
moisture, and the usual corrosive agents, and any damp- 
ness upon the bare plate be absorbed by the anti-corrosive 
paint, then it may be said almost all has been done that 
can be done by paint to prevent corrosion, and if any occurs 
it would appear, so far as present knowledge enables a judg- 
ment to be forming it can only be caused by moisture, or 
other corrosive influence that has previously permeated the 
pores of the metal, forming a nucleus of active corrosion 
aided by galvanic action brought about by inequalities in 
the texture and composition of the metal (Page 278). 

It is sometimes thought that all that is required in any 
paint is to keep the humidity of the air from the metal, but 
there are other objects, which will be stated; however, the 
extraction of any moisture that may be on the surface when 
it is painted is a most important one, or if water or moist- 
ure is confined in the pores or on the surface of the metal, 
corrosion is invited; hence oil paints and substances hav- 
ing no affinity for water are not to be particularly desired 



18 



for covering metals but those which have some power of ab- 
sorbing any moisture on or near the surface, and then become 
dry and elastically hard and finally set somewhat after 
the manner of Portland cement, although possessing greater 
adhesion and elasticity. 

As soon as the oil in oil paints has been exhausted the film 
of paint becomes a kind of porous plaster. In the case 
of bridges, which had been painted with red lead, the paint 
was universally brittle and very easily removed (Pages 279 
and 280). 

As all oil paint spread upon ironwork should not contain 
anything injurious to the metal, it would be well if it were 
analysed before being used. Naturally, no manufacturer of 
paints would desire to give a full analysis of the composi- 
tion of a paint. To meet this reasonable demur, a copy of 
the certificate of an analytical chemist might be presented 
with it, stating that no substance used in the paint had a 
corrosive effect on iron or steel. This would eliminate any 
paints that may be misnamed anti-corrosive paints (Page 
280). 

It is well to remember, in considering anti-corrosive 
paints, that in a chemical union the properties of the min- 
gled bodies are altered; in a mechanical admixture they 
are not, and, therefore, can be again separated. The impor- 
tance of a chemical union of the constituents of a paint is 
clear, for if the ingredients can separate they cannot form 
an even covering or be a water and air-tight coat. The 
uniform efficiency of a preservative coat will, in great meas- 
ure, determine the freedom from corrosion of a surface 
covered with it (Page 281). 

In the case of the bridges mentioned on page 280, it was 
found that the red lead paint was universally brittle and 
very easily removed, probably owing to the evaporation or 
oxidation of the oil. The white lead paint was also cracking 
wherever exposed to the sun. Oil paints do not long retain 
their preservative and anti-corrosive qualities, partly because 
the moisture of the condensed aqueous vapor on the surface 
coated gradually causes the permeation of the paint. Then 
corrosive action commences, and rusting occurs under the 
paint, and the latter becomes detached in time (Page 282). 

19 



Oil does not incorporate well with most pigments. Lead 
paints, even if they are to be preferred for any work, most 
certainly are not for any that is submerged, for water re- 
moves the cohesiveness given to lead paints by the oil 
(Page 283). 

The time is probably quickly coining when, except for in- 
door or the commonest purposes, while lead oil paint, i. e., 
white lead ground in oil, diluted with perhaps some linseed 
oil, turpentine and a little driers, added to make it dry 
quickly, will cease to be used for any engineering structure, 
except those of meanest kind, and its use simply be confined 
to domestic purposes and to coat things of little value, 
but which must be covered with something or other for sake 
of appearances (Page 284). 

The ordinary and old-fashioned* lead and oil paints are 
very seldom, indeed, now used for interior surfaces of iron or 
steel ships, some effective anti-corrosive composition being 
employed for that purpose (Page 284). 

To a certain extent, it may be said that paints are not 
unlike cements, which have several ways of becoming hard, 
viz., by drying, congealing by oxidation, in a few cases by 
cooling, and in others by becoming set by chemical changes. 
Oils are said to dry, not because of evaporation, but by 
absorption of the oxygen from the air. (Page 286.) 

Where ironwork is submerged or' occasionally submerged, 
approved anti-corrosive and anti-fouling paint, such as is 
used for ships' bottoms, should be employed, as it is especially 
manufactured to resist the effects of water and fouling. 
(Page 287.) ij 

- u i XL. s.A 

It is questionable whether boiled linseed oil of excellent 
quality, no oil being used containing any sulphuric acid, 
when thickened with pigments of earthy ochres, is not a 
sufficiently good paint for ordinary purposes, such as railings, 
lamp-posts, gates, and similar structures of inferior import- 
ance, but when the preservation of surfaces exceptionally 
exposed to deteriorating influences, such as corrosion, or 
fouling, has to be considered, other and more powerful pro- 

20 



tective coverings and compounds are required, not in the 
shape of a bulky and merely mechanical mixture of different 
materials, but a chemically combined substance which will 
not separate, peel, or allow moisture to penetrate; it also 
being free from deleterious ingredients, such as copper, mer- 
cury, sulphurous compounds, acids, or anything which pro- 
duces galvanic action, for it should have no chemical action 
on iron or steel. (Page 294.) 

Still, no oil paint can be said to be either durable or 
satisfactory for outdoor ironwork, for all oil paints become 
oxidised. (Page 295.) 

The reason of the flaking, cracking, and separation may 
be said to be that the paint, being sufficiently oxidised, ceases 
to be an impervious coating, the metal then becomes oxi- 
dised, rust forms, and the paint is dilated till its elasticity 
is destroyed; it consequently cracks, and finally flakes and 
falls off. It has been remarked that any substance used in 
paint which is an oxide may impart oxygen to the iron and 
promote oxidation, and, therefore, the paint, instead of being 
a protection, may be a more or less active source of supply of 
oxidising influences. (Page 296.) 

From the blistering, cracking, flaking, and falling away 
of oil paint when applied to a non-absorbent surface, as 
iron or steel, and the insolubility of oil in water, and, 
therefore, the absence of the property of suction, and con- 
finement of any water on the surface of a metal, its adhesion 
to the metal is always likely to be deleteriously affected, and 
certain advantages when it is applied to wood are disadvan- 
tages in the case of iron or steel; hence any substance, not a 
promoter of corrosion, that possesses greater power of adhe- 
sion is to be preferred in paints for coating metal. (Page 296.) 

Some delicate experiments by Mr. A. P. Laurie on the 
durability and protecting powers of oils and varnishes, de- 
scribed in a paper read before the Society of Arts, London, 
showed that linseed oil, however pure or carefully prepared, 
cannot be relied upon to protect a surface from moisture. 
Pesins seem to better prevent its access, but they are brittle 
and perishable. Varnish was found to be of little use, and 
mastic proved to be best of the substances tried. (Page 311.) 



21 



The average foreman will declare for lead paints whose 
compositions, as has been shown, is hardly conducive to anti- 
corrosive action, but it is a oil and lead paints" with many, 
or nothing. The reason is many know nothing of any other 
paint than oil and lead paints, which they have been accus- 
tomed to use perhaps from their boyhood. If any corrosion 
on the surface of the metal, cracking, blistering, or peeling 
should occur it may be roundly said it was to be expected, 
for another coat or two should have been applied, which is 
sure to cause a concensus of approval as more labor and 
materials are required. Any really carefully made paint of 
proved anti-corrosive and preservative ingredients is dis- 
liked, because it can only be made by experienced men, 
special processes and expert advice; and to not a few it is 
almost rank treason to use any other than oil and lead 
paints. Any cheap stuff that will show some body, and 
take up color, is made and approved, when it is impossible 
to buy the best materials of their respective kinds and 
properly manufacture a really durable anti-corrosive paint 
for the price at which it is required to be sold and delivered. 

The system of advertising for paint and accepting the 
lowest tender on a specification merely requiring "metallic 
paint," "oil and lead paint." "red lead and oil paint." "oxide 
of iron paint and oil," "red oxide of iron in oil," "thick red- 
lead paint," "two coats of oil paint, the first coat to be red 
lead and oil;" without any or with slight knowledge of the 
character and quality of the ingredients, has a vagueness 
which is most refreshing to a dealer, but can hardly be 
termed a satisfactory method of procedure, or conducive to 
the durability of a metallic structure, (Page 361.) 



EXTKACTS FROM "RUSTLESS COATINGS," 

By M. P. Wood. 

Published 1904 by John Widey & Sons. 

The essentials of a good paint, for whatever use intended, 
are: 

Eirst. — That it shall adhere firmly to the surface over 
which it is spread, and not chip or peel off. It must be non- 
corrosive to the material it is used, to protect, as well as to 
itself under long periods of atmospheric exposure and chem- 

22 



ical changes. It must form a surface hard enough to resist 
frictional influences, yet elastic enough to conform to all 
changes of temperature, or with a coefficient of elasticity 
approximately as near the material it covers as possible. It 
must be impervious to and unaffected by moisture, atmos- 
pheric or other influences to which the structure may be 
exposed. 

Second. — That it shall work properly during its applica- 
tion — a property which depends largely upon the relative 
amounts of pigment and liquid. The natures of both pigment 
and liquid also have influences that govern results. 

Third. — That it shall dry with sufficient rapidity. This 
function depends mostly upon the vehicle or liquid used with 
the pigment, though the pigment has in many cases an in- 
fluence, as will be seen further on. 

Fourth. — That it shall have proper durability, which is 
a function both of the pigment and liquid. And as the 
question of cost is in many cases the governing factor in 
the selection of a paint, the question of durability may be 
regarded as the most important one of the list. Is should 
be understood, however, that a paint can be durable per se, 
and not be protective in the strict sense of the word, as 
can be illustrated in the case of a good paint applied to the 
surface of a sheet of iron coated with rust. The liquid 
element in the paint will not absorb or neutralize the cor- 
rosion which it covers, But will dry regardless of it, and 
permit the destruction of the metal to progress beneath its 
coat. 

Fifth. — Covering power, by which is meant the power 
of a pigment so to cover the surface to which it may be 
applied that its protection from decay is not only assured, 
but that the minimum amount of paint shall effect this 
purpose. (Pages 1-2.) 

Oxide of iron is one of the strongest of pigments in cov- 
ering power. If one ounce of this pigment be spread in two 
coats over a given surface, say two square feet, so that the 
surface be completely hidden, and the job be declared a 
satisfactory one so far as covering power is concerned, and 
in the second case an ounce of the same oxide of iron be 
mixed with three ounces of barytes, kaolin, gypsum, etc., 
and this paint be spread over two square feet of surface 
as before, it is obvious that the amount of color per unit 
of surface will be the same in both cases ; but in one case 



23 



there is four times as much pigment as in the other, and in 
the second case three-fourths of the paint would be inert 
material. For railway ears and wooden structures the dura- 
bility of these paints would be in favor of the second case, 

as well as the cost of the paint. The pigment in this case 
is the life of the paint, and protects the oil from the decay 
incident to oxidation from atmospheric exposure. (Page 6.) 

Oxide of iron is practically unchanged after centuries of 
exposure. It induces and promotes oxidation in all organic 
substances with which it is brought in contact, and in nearly 
all metallic bodies. In an oxide-of-iron paint it is the oil 
which decomposes, it being the organic matter. The de- 
composition is due to the exposure of the elements aided by 
the oxidizing power of the oxide of iron pigment mixed with 
the oil. This statement holds true only where there has been 
no chemical change or combination between the pigment 
and the liquid- (Page 7.) 

Experiments determine that the most durable paints are 
those which contain a large amount of pigment per unit 
of surface; and that pigment is the best which is strong 
enough of itself, or with a proper proportion of inert mate- 
rial, to allow liquid enough to be added to it to flow and 
work well with the brush when applied. (Page 7.) 

The destruction of paint may be from eight causes: 
First, mechanical injury; second, the action of deleterious 
gases : third, chemical action between the pigment and the 
vehicle or liquid: fourth, chemical action between the body 
covered and the paint, either the pigment or the liquid; 
fifth, the action of light; sixth, peeling; seventh, destruction 
by cleaning; eighth, water. (Page S.) 

The action of deleterious gases is very familiar to those 
who have studied paints and protective compounds. Sul- 
phuretted hydrogen is one of the most common and active 
of these gases, and is formed in excessive amounts wherever 
coal is distilled for illuminating gas. Sulphurous acid fumes 
also, being disengaged in the combustion of coal in the 
many arts, transportation and manufacturing processes of 
the day: gases engendered in workshops, being of com- 
pound character carrying ammonia, carbonic acid, nitric 
acid, and other fumes, are active agents of corrosion to 

M 



metallic bodies, also to the paint compounds that cover 
them. (Page 9.) 

Hydrated oxide of iron (iron rust) oxidizes organic mat- 
ter (the oil) and gradually destroys it. (Page 10, Section 4.) 

Galvanized iron possesses the property of causing almost 
any paint applied to its surface to peel; in fact, it is one 
of the worst substances to cover with a pigment in a satis- 
factory manner. 

Various reasons have been given for this peculiar action of 
paint upon galvanized iron. One of the most plausible is that 
the use of sal-ammoniac in the process of galvanizing causes 
the formation of a thin film of the basic chloride of zinc on 
the surface of the metal being galvanized, which material, 
being of hygroscopic nature, acts as a repellant to prevent 
the close adherence of the paint to the metal, and the pig- 
ment dries as a skin over it. (Page 11.) 

Direct experiments show that dried linseed and other 
siccative oils, without pigment, are not resistant or water- 
repellant. When the oil is well dried, the application of water 
always causes the oil to assume a shrivelled appearance, 
showing that it has absorbed moisture and expanded and 
disintegration has commenced. (Page 14.) 

The ordinary test by master painters, of the ability of 
an oil or paint to resist moisture is to coat a surface, usually 
of glass, and when well dried, to immerse it in water for 
a few hours and note the changes in color and integrity of 
the paint. (Page 14.) 

To successfully design a paint which will resist all of the 
previously named destructive agencies, is a difficult matter. 
The field is an enormous one to cover and but little positive 
knowledge has yet been obtained, though the investigators 
and experiments have been legion, and the literature on the 
subject embraces volumes. Time is an essential factor in the 
test of the qualities of a paint. (Page 15.) 

Red lead paint, from the large amount of oil in it and 
its great specific gravity, spreads over a large area, and it is 
these features that cause it to run or craAvl on vertical or 
slichtlv inclined surfaces, narticularlv in the first coat. 



25 



A like result follows the use of ff ah e- graphite pigments. 
The atoms of this variety of graphite, on account of their 
smooth surface and low co-efficient of friction, appear to 
slide around in the vehicle before it dries enough to retain • 
them in position when spread. (Page 19.) 

It is to be regretted that this engineers views of what 
constitutes a thorough preparation of the ferric surface for 
its coat of paint is not an exception, but the rule in more 
than nine-tenths of the structural manufacturing establish- 
ments. ^Notwithstanding their claims to pre-eminence in their 
profession, they have yet to learn how to protect what they 
create; and that they are either incapable of this, or indiffer- 
ent to it, the present condition of the ferric structures of 
the day is an unanswerable evidence. 

If the superiors do not understand the importance of the 
proper preparation of the surface to be covered, or the char- 
acter of the paint and manner of applying it, or give them 
the same or more consideration than they attach to other 
matters of construction, it will be next to impossible for the 
inspector or master painter to enforce good work. It requires 
a more determined stand on the part of those in charge of 
this branch to ensure good work than in any other part of 
the construction details. TTntil the head officers are zealous 
enough to care something about the condition of the work 
after it has left the shop, and the men actually in charge of 
the painting are given to understand that they will have the 
unquestionable backing and support of their superiors in 
any stand they take against the present so-called practical 
methods of structural painting by the unscrupulous contract- 
ors, just so long will their work show their neglect in the 
rapid progress of corrosion, that will not need scraping 
the surface of the coating to find. (Page 21.) 

However consistent and beneficial the first coating of oil 
may be for a wood or masonry surface, it has no part or 
parcel on a metallic one. when applied for the correction of 
the mill-scale evil. Xo number of these oil or even paint 
coatings will soak into and bond these scales together, or to 
the metal surface. There are hundreds of records of the 
painting of important railway structures, where the first 
coat of boiled-oil method was used, and, in the great majority 
of instances, the utter and rapid failure of the coating, 



26 



and the extra corrosion of the structure, could be directly- 
assigned to this so-called method of protection. 

The weather-resisting power of an oil coating is almost 
nil compared with a paint, as before referred to in Dr. 
Dudley's experiments. If the advocates of oil coatings are 
so sure of its benefits as against a paint, why not make all 
the coatings of oil alone, no matter what it covers, a wire 
or an anchor? It will soak as far into one as the other. 
(Pages 24 and 25.) 

Too much oil in a paint coating, particularly if the sur- 
plus oil is in or near the foundation coat, whether on a 
wooden or metallic surface, will generally cause peeling re- 
gardless of the pigment used in the coatings. (Page 25.) 

Red lead is one of the heaviest and most expensive pig- 
ments, also the most difficult to prepare for a paint or to 
spread. It is more susceptible to adulteration, and is more 
adulterated by interests inimical to its reputation, than any 
other pigment, with the possible exception of its sister- 
product, white lead. (Page 47.) 

Red lead compositions are extensively advertised to keep 
indefinitely without setting, and that are ready for use at 
any time without further mixing or preparation. In all such 
mixtures, the red lead, or the oil, or both, are adulterated 
and will be found to be comparatively short-lived and un- 
reliable whatever may be the guarantee, which in general 
lays more stress upon the extraordinary large sur- 
face that can be covered than the permanent character of 
the coating. As well expect a hydraulic cement ready mixed 
to be a suitable article for engineering use as an "always- 
ready" red lead paint. (Page 56.) 

The natural drying of a linseed or varnish coating is 
in the form of a closely woven web of a fine fabric. This 
shows plainly on a freshly dried or drying surface, and 
explains the reason why two or more coats are necessary to 
give a smooth foundation for the last or polishing coat. 
Each subsequent coat fills the interstices of that underneath 
it, each coat repairing the other's deficiencies, as many folds 
of a fine muslin will in the aggregate make an adequate cov- 
ering from heat or light. 

27 



Now, it is the function of a pigment to fill these cellular 
formations in the drying vehicle, or rather, while being 
applied with a brush, for the atoms of the pigment, me- 
chanically arranged in brushing out the paint, to lie side 
by side, all embedded in the vehicle, which in drying nat- 
urally takes the lines of least resistance, i. e., between the 
pigment atoms, and, as it were, each atom lies in an approxi- 
mately square hole, the most favorable condition for the bond 
between the pigment and the vehicle. (Pages 139-140.) 

Note. — The author here shows conclusively that graphite 
and linseed paint manufacturers do not dare recommend one 
coat of paint for the preservation of steel. It is, as the 
author says, like a piece of muslin, full of holes, no doubt 
caused by oxidation when it is put upon the steel and they 
depend upon the protection of the steel by successive coats; 
but carbon di-oxide will penetrate the porous coat and then 
attack the others, and finally reach the steel, proving our 
statement that all paints mixed with oil and that dried by 
oxidation, tend to corrode the steel. 

As regards porosity of hydraulic cement refer to pages 
155 and 156. 

Bloxam's "Chemistry," edition 1895, pages 376 and 377, 
states "that the ordinary corrosion of iron is accomplished 
only in the presence of moisture, air and C0 9 . If any of 
these substances are absent the corrosion cannot take place. 
(Page 156.) 

It is, therefore, only necessary to have a limited amount 
of some acid present with air and moisture to cause the 
ultimate destruction of a large amount of iron, because the 
C0 2 or other acids present never become fixed, but are 
always active, passing from molecule to molecule, as long 
as there is any free metal for them to attack. (Page 157.) 

Even a cement free from the sulphur element, if mixed 
with a small quantity of cinder, or if lain in soil containing 
cinders or pyrites, will absorb the acid and collect it in dan- 
gerous amounts in the voids of the concrete. Once there, it 
will ultimately reach the metal and cause the failure of the 
grillages by the columns or other superincumbent load punch- 
ing through the foundations. The?e conditions are further 
aggravated by the fact that nearly all ground-water is 

28 



charged to some extent with saline or sulphur elements or 
both, that would soon saturate any alkaline substance pres- 
ent in the cement. When this point is reached corrosion 
of the grillage will inevitably ensue even if the imposed 
columns show no evidence of its action. 

Grillage ironwork has been removed from concrete foun- 
dations laid only five years and found to be corroded | inch 
or more over its whole surface. 

The thickness of grillage beams is seldom i inch, so 
that thirty or fifty years will practically limit the safety of 
many of the modern steel skeleton structures. (Pages 
157-158.) 

Professor Charles L. Norton, excerpts from Third Re- 
port, 1902, says: "In both the solid and porous cinder con- 
crete many rust spots were found, except where the concrete 
had been mixed very wet, in which case the watery cement 
had coated nearly the whole of the steel like a paint and pro- 
tected it." (Page 159.) 

The wires of the anchorage ends of the cables of the Niag- 
ara Palls Suspension Bridge were opened for a short dis- 
tance where they entered the anchorage pits. These ends 
were embedded in hydraulic cement, and at the end of forty 
years many of them had become so corroded that the strength 
of the structure was seriously impaired. 

In this case and with all ferric material embedded in 
concrete, the caustic action of the usual make of cement 
whether damp or wet, will furnish the carbonic acid necessary 
to destroy any linseed-oil coating or paint that covers them 
and induce corrosion. (Page 160.) 

That metal needs some additional protection from the 
caustic action of the impure cements too frequently em- 
ployed, also from the quick-lime mortar beyond the usual 
coat of paint is recognized. (Page 160.) 

How far the protection of ferric foundations, either near 
or below the water line in the many structures already built, 
or in progress in all parts of the world, has been considered 
by their architects and engineers time only will reveal. For 
those proposed, like the miles of rapid transit and railway 
tunnels, a great portion of which will be carried through 

29 



ocean silt or salt inarsh mud and exposed to the most virulent 
form of corrosion, some more positive and effectual means 
of protection from corrosion must be employed than has ever 
been adopted. No wash or trowel coating of cement, good or 
bad, or applied in mass, will avail for but a short period to 
protect the metal that these structures must rely upon for a 
great part of their strength. 

The hardness and inelastic character of cement or mortar 
coatings will cause them to crack under the vibrations in- 
evitable to all railway structures; and while resisting water 
in mass, they will absorb moisture sufficient to be always 
damp and in that condition are of the least strength. 

The present method of constructing buildings wholly or 
in part of steel framing and concrete, avoiding the use of 
brick and stone masonry as far as possible, is causing a great 
deal of anxiety among architects and engineers as to the 
future state of the metal so embedded. 

At a late meeting of the English Architectural Associa- 
tion, Mr. H. Humphrey gave as a result of his experience 
that metal buried in concrete containing furnace cinders or 
coke breeze, should be coated with Dr. Angus Smith's Anti- 
corrosive compound, or some other compound containing 
pitch and sand ; that some samples of cinder concrete analyzed 
as high as three-fourths of one per cent, of sulphuric acid. 
A case was cited by another member of the association where 
a hot water pipe laid in cinder concrete was rotted away in 
a very short time. 

The cinder concrete used in the floors of the steel frame 
sky-scrapers in ISTew York City invariably shows the presence 
of sulphuric acid strong enough to redden litmus paper. 
(Pages 159-160-161.) 

Gas pipes embedded in plaster of Paris (gypsum) have 
been found to be completely corroded in a few years. 

The use of gypsum in cement to hasten its setting is 
detrimental. Gypsum is soluble to some extent in water, 
besides it contains water from its hydration, which absorbs 
carbonic acid from the air that quickly causes corrosion. The 
rust so formed absorbs moisture and carbonic acid and fur- 
ther hastens the corrosion. 

The screwed ends of all pipes are invariably attacked. 
They are of bright metal only about 1/16 inch thick and 
seldom, if ever, have even a brush coating of any paint to 
protect them when put up or left in place. Galvanizing the 

30 



fittings and body of the pipes does not protect the screwed 
ends; the corrosion at these points is only hastened by the 
galvanizing. 

The effect of corrosion upon the floor beams and other 
structural parts used in modern architectural work has been 
the subject of discussion by the American Society of Archi- 
tects, the consensus of their opinion being expressed by one 
of the prominent members as follows: 

"With regard to the strength of the steel cage construc- 
tions, both as to wind strain and other disturbing strains, 
there is no question. All objections arising from these points 
have been overcome, but unless exceptional care is taken in 
the construction to protect the steel cage, particularly at its 
joints, from corrosion, this class of buildings will not be 
permanently safe. It is perfectly feasible, with great care, 
to protect the steel frames from corrosion, but I am con- 
vinced that many high buildings have been put up in this 
country where the proper care in this respect has not been 
taken nor the necessary preventatives against corrosion 
applied." (Page 161.) 

On the 12-inch steel I beams carrying the sidewalks 
around the Pabst Hotel in New York City, and that were 
removed after being in place less than six years, corrosion 
was in active progress. The space beneath the beams was 
used as a cafe, always dry and heated. Wherever the brick 
work came in contact with the beams in all of the stories, 
the paint was dead and corrosion established. This was par- 
ticularly noticeable in many portions of the beams where the 
usual top dressing of coal cinders had been laid to level up 
the arches forming the foundation for the artificial stone 
sidewalk. The rivets that held the corner angle-irons to the 
beams were nearly all loose from the corrosion around their 
heads or points and had lost their set or draw. (Pages 
161-162.) 

Note. — (Page 246.) The author says that "paint dried 
solely by evaporation through the other skin of the paint, 
leaves pores." 

Figure 36 shows the mill-scale corrosion on one of hun- 
dreds of New York elevated railway columns, originally 
painted with red lead. The corrosion now in progress is 
strong enough to break through and cast off six or more paint 

31 



coatings that have been applied over the red lead since the 
columns were placed in position. (Pages 262-263.) 

The decay of a paint is hastened by mechanical action 
if the water, either fresh or salt, or the other solutions, are 
in motion. Ordinary commercial oil coatings are destroyed 
by diluted muriatic and nitric acids, alkaline liquors, am- 
monia, sulphide of ammonium, soda, caustic alkalies, and 
alkaline solutions of coal ashes, clinkers, cinders, soot, etc. 
(Page 264.) 

A coating of paint appears to be a very simple thing, 
as it is, when applied to a house or barn and both are left to 
their fate, but when applied to an important engineering 
structure, with all the vicissitudes of service in the extremes 
of heat and cold, sunshine and storm, atmospheric and other 
gases from natural or manufacturing sources, from corrosive 
liquids and solids, it is a different matter, and requires more 
engineering experience to select, more chemical knowledge 
to compound, and more technical details to get the right thing 
in the right place at the right time, in the right manner, and 
in the right amount than the general run of master painters 
do or can give to the subject. If the influences to whiKh a 
coating of paint is to be subjected are known it can generally 
be determined in advance whether it will be durable. (Page 
265.) 

Red lead (Pb o 4 , specific gravity, 9.07) remains un- 
changed under ordinary atmospheric conditions, but if the 
air contains hydric sulphide, as it doeskin many manufactur- 
ing establishments, and towns, to a notable extent, it will by 
an inexorable chemical law change the oxide to a sulphide of 
lead (PbS, specific gravity, 7.13) and this chemical change 
(usually denoted by the blackening or discoloration of the 
coat) will also be accompanied by an increase in volume of 
the sulphide of about 22 per cent., this increase acting 
mechanically to disturb the bond between the pigment vehicle 
and surface coated. (Page 265.) 

The English encyclopedia of painting, the edition of 1880, 
states under the head of "Pigments": All pigments can be 
grouped into three classes, according to their affinity for 
linseed oil. 

First. — Those that form chemical combinations called 
soaps, etc. 

32 



Second. — Pigments of this class, being neutral, have no 
chemical affinity for the oil; they need large amounts of 
driers, either combined with and carried by the oil, or as 
free driers. They include all blacks, graphites, slates, slags, 
vermilions, Prussian, Paris, and Chinese blues, terra de 
sienna, Vandyke brown, Paris green, verdigris, ultramarine, 
carmine, and madder lakes. The last seven are transparent 
colors and are better adapted for varnish mixtures and 
glazing. 

Third. — Pigments of this class act destructively to lin- 
seed oil. They have an acid base (mostly tin salt, hydro- 
chloride of tin and redwood dye) which forms, with the 
albuminous and gelatinous matters in the oil, a jelly-like 
compound that does not work well under the brush nor 
harden sufficiently, and can be used in a varnish for glazing 
only. Among the most troublesome are the lower grades 01 
so-called carmines, madder lakes, rose pinks, etc., wnich 
contain more or less acidulous dyes, forming with linseed oil 
a soft paint that dries on the surface only and can be peeled 
off like the skin of ripe fruit. (Pages 266-267.) 

"Catalysis" is a term introduced by Berzelius, and by 
him applied to the changes that sugar solutions undergo in 
the process of fermentation, and now used to denote the 
changes that certain substances, by their mere presence, effect 
in other bodies without themselves undergoing any apparent 
change. Catalytic action is a potential agent in the decay 
of paint coatings, and manifestly has not received the atten- 
tion from paint chemists and compounders that its marked 
action on the life of a coating warrants. (Page 267.) 

Combustion of any substance may be quick and attended 
by a high temperature, as in the case of the incandescent gas 
light, or it may be of a low temperature and extend over 
years of time, but the amount of heat evolved from the 
destruction of the substance and the resultant products of 
combustion, or decomposition, are the same in all cases, even 
if the physical effects are apparently different. 

Nearly every substance in a paint coating has been found 
to be catalytic to some other substance, either in its own class 
as a so-called inert mineral pigment, or in the chemical class 
of oxides having a lead, zinc, iron, or other metallic base. 
Individually, they may be apparently unaffected by a long 
exposure to the air while in their loose state or in packages 

33 

LofC. 



of bulk; but when mixed together, they take up moisture or 
oxygen to a greater or less degree, either by absorption in 
mass or by condensation upon their surfaces, and satalytic 
action ensues. The oil vehicle and driers are catalytic of 
themselves, and when mixed with the pigments act more 
energetically as carriers of oxygen even when the coating is 
apparently dry. (Pages 267-268.) 

Note. — For the United States Navy Yard tests in 1884 
see pages 286-293. 

Apropos of United States Navy Yard tests, we respect- 
fully refer to pages 405, 406, 407, in detail, a table showing 
results of tests of protective coatings applied to steel and 
aluminum plates immersed for thirteen months at Brooklyn 
Navy Yard, taken from Engineering News, Volume XL, 
No. 4, July 28, 1898. 

Plate No. 274, Mclnnes Paint. The American Mclnnes 
Composition, manufactured by George N. Gardiner & Son. 
The record speaks for itself. At the present time there are 
only two other compositions, as we believe, used by the 
United States Navy: Kahtjens' Paint, Plate 273. The Inter- 
national Holzapfel Plate 275, page 407, Volume 7. 

At an annual convention of the American Institute of 
Architects, in a discussion on the use of iron and steel in the 
construction of modern high buildings, it was reported by 
one of the leading architects in the United States that the 
iron beams removed by him from the old Times building, 
though in use only thirty-five years', were rotten with rust. 
They were enclosed in eight inches of brick work, forming 
the arches that supported the pavement over the vault where 
the steam boilers were placed, and though always dry, yet, 
had been exposed to ordinary fire-room vapors. They had 
been well painted with iron-oxide paints and protected from 
external moisture by an asphalt covering. The iron came 
off in strips, clearly showing that the rust had followed the 
lamination of the iron, the web of the girders being so rotten 
as to be easily broken by the fingers. Other examples of 
sidewalk beam corrosion are given on page 269. (Page 334.) 

A paper read at the thirtieth session of the Institution of 
Naval Architects by Professor Vivian B. Lewes, P. R. S., 
F. I. C, Royal Naval College Associate, April 12, 1889, and 



34 



published in full, Scientific American Supplement, Vol. 
XXVIII, No. 709, August 3, 1889; pages 11, 320. (Page 
340.) 

Professor V. B. Lewes, of the Royal Naval College, 
Greenwich, England, at a recent meeting of the Institute of 
Naval Architects, London, states: 

"The rusting of iron and steel is a definite chemical pro- 
cess, due to the conjoint action of the air, moisture, and 
carbon dioxide upon the metal." (Page 340.) 

M. 3, OhevreuVs Experiments. 

These experiments of Mr. Neil were followed by the ex- 
periments of Mr. M. E. Chevreul, who contributed a paper 
in 1856 to the Annates de Chime, corroborating Mr. Neil's 
deductions upon the drying of siccative oils, and by him 
clearly laid down, viz. : 

Eirst. — That it is the absorption of oxygen by the sicca- 
tive oils and the change of the oleic, margaric, and stearic 
acids of which they are composed and the chemical combina- 
tion with each other in the presence of oxygen into the 
linoleic and linolenic acids, that is the cause of their solidi- 
fication, which term he thinks more clearly defines the action 
of the oil than drying, which in general may mean evapora- 
tion, which is a term adaptable to all liquid bodies, or rather 
indicates the removal of liquid from all bodies. This defini- 
tion appears to be apropos to many of the latter day cheap 
mixtures called paints; the difficulty experienced with some 
of which is not to have them dry in a reasonable time, but to 
have them keep liquid long enough to spread them at all. 

Second. — That the oxidation of the oil is a chemical pro- 
cess and naturally inherent in itself. The action of heat, as 
in boiling, hastens the drying or resinification of the oil by 
removing the water and mucosities. That all substances 
which can be used as driers must be such as are capable of 
parting with oxygen or dissolving in it; and being of them- 
selves oxidizable in combination, they in that way increase 
its absorptive power. There is a class of driers (white 
copperas, for instance) which act catalytically, while 
mechanically suspended or in contact with the oil, and in- 
crease its oxygen absorptive power by their presence, but 
leave no increase of drying power when withdrawn. (Page 
226.) 



35 



SEP 20 1904 



The influence of heat in drying a paint or varnish is 
apparent when it is considered that in the ordinary drying 
of either to a firm, hard coating, 21 per cent, of oxygen has 
been absorbed from the atmosphere or driers, yet a further 
exposure to the heat of the sun until the coating becomes 
hard and resinous ensures a loss of 3 to 5 per cent, of this 
amount. (Page 236.) 

One difficulty lies in procuring a chemically pure oil to 
make the comparison with the reactions caused by sulphuric 
and nitric acids, and caustic soda treatment for the color 
changes in the sample tested. The linseed for such an oil 
must be picked over with the greatest care, selected from 
fully ripe and full weight seeds, and pressed in seed bags 
that have never been used before. 

The result of an application to a large number of the most 
responsible oil seed pressing firms, was that not one could 
furnish a sample with less than 5 per cent, of other seed oil 
in it, and most of the best commercial brands contained over 
12 per cent. (Page 240.) 

Mineral oil or petroleum in any form cannot be added 
to linseed oil to exceed 5 per cent, without affecting its dry- 
ing; and 10 per cent, prevents its drying other than as a 
thin skin impervious to the air, and the oil remaining 
green beneath is liable to blister or peel on exposure to sun- 
light. It does not bond to the pigment or surface coated. 
(Page 241.) 

Probably 80 per cent, of all the oils, paints, and varnishes 
manufactured in the world is applied to structures of minor 
importance, which are destroyed by causes other than corro- 
sion. These coatings are quite as much for looks as for 
physical condition, but the other 20 per cent, is used on the 
most important and costly engineering structures of our 
time. These require protection from corrosion from the hour 
the materials leave the rolling mill, forge and foundry until 
they are in the finished structure, and need more then than 
during construction. (Page 248.) 



36 

(N1053) 



LIBRARY OF CONGRESS 



019 408 491 2 & 



